Hi guys,

I have a zencart site that's been running for ages, but it recent times there has been more occurrences of DPS payments showing up in the bank account without a corresponding order in Zen Cart.

After much investigation by Payment Express, myself and my web host, we're left scratching our heads a bit.

First off I've checked the permissions of dps_pxpay_result_handler.php and can confirm that they're 755

What happens on checkout is we're redirected to the DPS page, enter the card details and once the transaction is complete DPS sends the http GET (FPRN) to the web server, which then returns a 404 error.

If the user clicks the next button on the DPS page, the exact same http GET (although from the users IP address rather than the DPS server) is sent which returns a 302 and successfully completes the payment and checkout process.

Note: the problem here is we want the FPRN to work incase the user doesn't click next or has a problem with their browser.

This is the FPRN which gets a 404 response:
203.207.60.XXX - - [20/Sep/2012:16:53:09 +1200] "GET /dps_pxpay_result_handler.php?result=v51Hma1nTBEraTNJgxFD8M55mugVx0zFr8eJLA0IPwMw 4oIaCuZdKWj2oVkvqV5iS9_FUZkXSn9rCq9TJLhhImeTwUPJ9Z3Dv0cvyMgwADHNd-1gzFxQTjFkGszSCCBw_B62RbLHemrYsOqhNQPbN_dPx-On0cbsw8R7Mom5yxxM8TrMcdfrxJNp2MF_QNCQGRx_z6_WBE0ner9xCMfZtsE6-1YfU_rmoz_fcJmXQP36kf7iiZnvBOQgQsca2rckfZBw6HXAUG0CN0L6vjMAybDibKQAv7F67Ggb2N9E3 CWv_7sMF8N9OFNVvZwMLqfN3e2lWXZPVChufrFuBZDRQtVO7wE2y8EzuA-mnJtttbGxB7g6tl2Bz7m0nCnwH3rjRTGqw3ERsMkMJUqKMEVFnmk18PiGVbjI6SrS94IYzGtthIcEeWz XhIBOJ5DCdc217-TEWUniO3t1b9xlfivIGMsTxX7QYHVjDlAGxXsHH0q2Wn8wb0jfnWaSVxz8PrXJIQTY4l06QaQm5_CzcB M5HFfPRTGm3kmBdPa7kJt9_ng3Q=&userid=Fxxxxx HTTP/1.1" 404 465 "-" "PXL1"
and this is the successful GET that happens after the user clicks 'next' on the DPS payments page:
121.72.214.XXX - - [20/Sep/2012:16:53:39 +1200] "GET /dps_pxpay_result_handler.php?result=v51Hma1nTBEraTNJgxFD8M55mugVx0zFr8eJLA0IPwMw 4oIaCuZdKWj2oVkvqV5iS9_FUZkXSn9rCq9TJLhhImeTwUPJ9Z3Dv0cvyMgwADHNd-1gzFxQTjFkGszSCCBw_B62RbLHemrYsOqhNQPbN_dPx-On0cbsw8R7Mom5yxxM8TrMcdfrxJNp2MF_QNCQGRx_z6_WBE0ner9xCMfZtsE6-1YfU_rmoz_fcJmXQP36kf7iiZnvBOQgQsca2rckfZBw6HXAUG0CN0L6vjMAybDibKQAv7F67Ggb2N9E3 CWv_7sMF8N9OFNVvZwMLqfN3e2lWXZPVChufrFuBZDRQtVO7wE2y8EzuA-mnJtttbGxB7g6tl2Bz7m0nCnwH3rjRTGqw3ERsMkMJUqKMEVFnmk18PiGVbjI6SrS94IYzGtthIcEeWz XhIBOJ5DCdc217-TEWUniO3t1b9xlfivIGMsTxX7QYHVjDlAGxXsHH0q2Wn8wb0jfnWaSVxz8PrXJIQTY4l06QaQm5_CzcB M5HFfPRTGm3kmBdPa7kJt9_ng3Q=&userid=Fxxxxx HTTP/1.1" 302 542 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/536.26.14 (KHTML, like Gecko) Version/6.0.1 Safari/536.26.14"
According to my eyes, the only differences between the two GET's are the source IP address and the user agent / OS info.

in the dps_pxpay.php module the comments on line 72 suggest that FPRN is supported
// support for fail proof result notification
$this->_dpsResultRedirect = ('true' == ENABLE_SSL ? HTTPS_SERVER : HTTP_SERVER) . DIR_WS_HTTPS_CATALOG . 'dps_pxpay_result_handler.php';
// without
#$this->_dpsResultRedirect = zen_href_link(FILENAME_CHECKOUT_PROCESS, '', 'SSL', false);
Any ideas about how to resolve this issue?

Thank you,

Brendon